Filtration and circulation system for maintaining water quality in mariculture tank

ABSTRACT

A filtration and circulation system for maintaining the water quality in a fish tank favorable for promoting the production and growth of fish therein and for circulating water therethrough at a rate designed to provide a high rate of water exchange in the tank. The system includes particulate, biological and activated charcoal filters serially arranged in pressurized and unpressurized sections thereof for converting or removing ammonia, waste food and excrement from the water. In addition, parallel flow paths from these filters through a protein skimmer and an ultraviolet sterilizer section, respectively, are provided for lower volume treatment of the water being circulated therethrough.

United States Patent Sanders 1 1 May 9, 1972 54] FILTRATION ANDCIRCULATION 3,116,712 1/1964 Ogden et a1 ..119 5 SYSTEM F R MAINTAININGWATER 3,513,978 5/1970 Newsteder 1.210/169 QUALITY IN MARICULTURE TANKPrimary Examiner-Charles N. Hart Attorney-Oblon, Fisher & SpivakABSTRACT A filtration and circulation system for maintaining the waterquality in a fish tank favorable for promoting the production and growthof fish therein and for circulating water therethrough at a ratedesigned to provide a high rate of water exchange in the tank. Thesystem includes particulate, biological and activated charcoal filtersserially arranged in ressurized and unpressurized sections thereof forconverting or removing ammonia, waste food and excrement from the water.in addition, parallel flow paths from these filters through a proteinskimmer and an ultraviolet sterilizer section, respectively, areprovided for lower volume treatment of the water being circulatedtherethrough.

16 Claims, 3 Drawing Figures PARTICULATE 7 PROTHN Hum 21 SKIMMER 20 ll17 23 22 I I i BIOLDGICAL 26 OVERFLOw-m", 1-

l 40 FILTER 1 ULTRAVIOLET l IRRADIATION 0 1 IO I 1 1 f 3 44 I i 1 i iSUMP 34 29 28 I v 39 (25 34 f 34 TANK 3s 37 a m :1 36 PARTICULATE FILTERPATENTEDMAY 9|972 3,661,262

sum 2 BF 2 FIG. 3

[NV zu'rons GRAHAM SANIIRS ATTORNEYS FILTRATION AND CIRCULATION SYSTEMFOR MAINTAINING WATER QUALITY IN MARICULTURE TANK BACKGROUND OF THEINVENTION This invention relates to the production and raising of foodfish and,more particularly, concerns a filtration and circulation systemfor maintaining the water quality in a fish tank favorable forencouraging the production and growth of fish and for circulating watertherethrough at a rate which is designed to provide a high rate of waterexchange in the tank.

An ever-increasing demand for food fishes and the protein derivedtherefrom has given rise to increased interest on the part of commercialconcerns in the farming,or raising,of the same. The pompano, which isabundant in southern states during certain seasons, is one of the mostdelicious of the salt water food fishes, brings premium prices,andtherefore is one of the most highly sought-after of the food fishes. Forthese reasons,also, it is probably the most attractive of all formariculture.

Accordingly, the pompano has become the subject of very activemariculture study in recent years and various processes and techniqueshave been advanced for spawning,hatching and raising these fish undercontrolled environmental conditions which are designed to promoteincreased production and rapid growth thereof. Thus, free-circulatingponds open at both ends to tidal flow for introducing fresh sea waterhave been prepared and attempts have been made to promote the growth offish in the pond by providing supplemental food and controlling waterconditions by pumping tidal water therein.

More desirably, of course,the provision of a closed cycle fish tank, orfish tank system, wherein the environmental conditions of the watercould be maintained most favorable for a specific phase in the fishproduction process, such as, for example, spawning,hatching,or raisingof the fish,would permit greater control over the entire fish productionprocess to be exercised. In such closed cycle fish tank systems,however,there is presented the problem of maintaining the proper waterquality and of providing a reasonable circulation rate which isessential in mariculture, especially in pompano mariculture. Variousfilter arrangements have been proposed, but these have either beeninadequate for maintaining good water quality, or, in the effort to doso, they have failed to achieve a sufficiently'high flow rate.

SUMMARY OF THE INVENTION Accordingly, it is an object of the presentinvention to provide a closed cycle fish tank and water circulationsystem having means associated therewith for maintaining the waterquality therein favorable for increasing the production and growth offish and for circulating the water through the tank at a rate sufficientto provide a relatively large number of tank water exchanges in eachday.

Another object of the present invention is to provide an improvedfiltration system for maintaining the water quality in a fish tankfavorable for increasing the production and growth of fish therein.

Still another object of the present invention is to provide an improvedfiltration and water circulation system for maintain ing the quality ofthe water in a fish tank favorable for increasing the production andgrowth of fish therein and for circulating the water through the tank ata rate which is sufficient to provide a relatively large number of tankwater exchanges in each day.

In accordance with the principles of the present invention,the foregoingand other objects are achieved by a combination water qualitymaintenance and circulation system which comprises, in association withthe fish tank, a particulate filter and a biological filter which areserially connected, in vertically arranged relation, through a sump to abank of activated charcoal filters, and means for pumping water from thetank to the particulate filter and from the sump to the activatedcharcoal filter bank. By-passes, or parallel flow conduits,are providedfor detouring a portion of the main flow through a protein skimmer,or adevice for removing high- I molecular-weight organic material, en routeto the particulate BRIEF DESCRIPTION OF THE DRAWING Various otherobjects, features and further attendant advantages of the presentinvention will be more readily appreciated as the same becomes betterunderstood from the following detailed description when considered inconnection with the accompanying Drawing wherein like reference numeralsare used for designating like or corresponding parts in the severalfigures, and in which:

FIG. 1 is a schematic diagram of a filtration and circulation system inwhich the present invention is embodied;

FIG. 2 represents a novel particulate filter arrangement that is usefulin the practice of the invention; and

FIG. 3 represents a modified arrangement of the particulate filterillustrated in FIG. 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Referring now to thedrawing and more particularly to FIG. 1, there is shown a filtration andcirculation system for maintaining the water quality in a fish tank 10favorable for encouraging the production and growth of fish and forcirculating water therethrough at a rate designed to provide a high rateof water exchange in the tank which, being constructed in accordancewith the teachings of the present invention, comprises a pump 12 beingconnected on the inlet side thereof to a fluid outlet pipe 13 from thetank 10 and on the outlet side thereof to a conduit 14 for deliveringwater from the tank 10 to the first stage of the filtration system.

The delivery conduit 14 connects with an inlet pipe 16 of a particulatefilter I7 and with an inlet pipe 18 of a protein skimmer 20 ofconventional design which serves to remove high molecular weight organicmaterial from the water, which are toxic and would be dangerous to thefish if they were carried again into the water of the tank 10. Theoutput of the skimmer 20 is returned to the main flow of water from thetank 10 for passage through the particulate filter 17 through a conduit21.

Disposed below the particulate filter 17 is a biological filter 22 forreceiving water descending by gravity from the particulate filter 17through a conduit 23 connecting the lower portion of the particulatefilter arrangement 17 with the upper portion of the biological filter.The biological filter 22 may be composed of a bed of sand and shells inwhich bacteria utilize the ammonia in the incoming water, which isconstantly being produced in the system by excretion of fish animals andby the breakdown of organic substances in the culture medium, orwater,for converting the same through an oxidizing process to thenitrite and then to the nitrate form. The bed is supported by somewater-permeable substrate mesh or framework which permits the water todrain therethrough to the bottom of the biological filter container,fromwhere it may flow, still under the effect of gravity, through a pipe 24and into a sump 25 positioned therebelow.

An overflow pipe 26 is provided in the upper region of the biologicalfilter 22, above the sand and shell bed therein, for passing anyoverflow to the sump 25 and thereby eliminating any excessive build-upof fluid in the filter 22 and maintaining adequate flow through thesystem.

Pressurized flow of water from the sump 25 is directed by a pump 28,connected at its inlet side to the sump 25 by a pipe 29, through anoutlet pipe 30 and into divided conduits 31 and 32 branching therefrom.The main body of flow,or the larger portion of flow being moved by thepump 28 through its outlet 30,passes through the pipe 32 and into amanifold 33 which feeds a bank of activated charcoal, or resin, typefilters 34. This filter bank comprises a plurality of closed containersin which the water if forced through a bed of charcoal or resin, inorder to remove the nutrients, such as, for example, nitrates andnitrites, as well as any remnant ammonia. If desired, several of theelements may be used in parallel to increase capacity, and additionalmanifolds and filter banks may also be added as needed. I

The outputs of the charcoal or resin filters 34 are collected in anothermanifold 36 and are conducted through a pipe 37 and another particulatefilter 38, for removing any particles of filtration material, to aninlet pipe 39 of the tank 10. Obviously, the water tank input pipe 39can be arranged to generate desirable circulation characteristics in thetank 10, and preferably is provided with means for aerating the filteredwater flowing into the tank, such as, for example, a venturiarrangement, primarily for maintaining a good level of dissolved oxygenin the tank.

The portion of the flow being tapped off between the pump 28 and themanifold 33 and routed through the pipe 31 passes through an enclosure40 for being treated with ultraviolet radiation. From the ultravioletsterilizer 40,this part of the flow is conducted through a pipe 41 andreturned thereby to the tank 10. Thus, a portion of the flow iscontinuously tapped off and treated with ultraviolet rays for furtherpreventing the build-up of bacteria in the system.

The sump 25 is simply a reservoir which helps to maintain the desiredcirculation rate through the system. This is facilitated by a siphonpipe 43 connecting the sump 25 and the main tank which is continuouslyprimed to provide a balance between the pumps 12 and 28, and thereby inthe case of an overflow in one part to conduct water from the sump tothe tank and, alternatively, from the tank to the sump. The siphon pipe43 is preferably provided with a particulate filter 44, such as, forexample a screen of 50 micron aperture nylon mesh, for preventingparticulate matter from reaching the last stages of the filter system,orthe filter bank 34, through the sump 25. In addition, as a means toprevent bacteria build-up in the system, the water in the sump 25 may betreated with ozone, which may be generated in a commercial ozonizer andpumped into the sump.

Referring now to FIG. 2, there is shown a preferred embodiment of theparticulate filter 17 which may be used in the filtration andcirculation system of the present invention. As shown, the particulatefilter 17 comprises a housing 45 having inlets 16 and 21 in the upperregion thereof through which flow is received, respectively, from thepipe 14 and the protein skimmer 20. A series of verticallystacked,horizontally disposed screens 46, 47, 48, and 49, consideredfrom top to bottom,which are made of monofilament synthetic polymerfibers such as nylon, and having apertures ranging from approximately600 microns for the top screen 46 to 50 microns for the bottom screen49, are supported in the housing 45 on annular brackets, not shown, orthe like. The screen 46 is disposed about 2 inches below the level of anoverflow outlet 50 whereby, in the event it should become clogged,thewater being fed into the housing 45 through inlets 16 and 21 may bypassthe screen 46 and immediately descend to the screen 47 therebelow.Similarly, overflow outlets 51 and 52 are provided above the screens 47and 48, respectively, for permitting flow to bypass these screens in theevent they should become clogged.

If the bottom,finest mesh screen 49 should clog an overflow pipe 55 isprovided, having an outlet from the housing 45 approximately 2 inchesabove the level of the screen 49, for routing the water back to the maintank 10. This prevents particulate matter from contaminating theremainder of the filtration system.

If desired, an alarm may be added to indicate clogging and overflow, ora second particulate filter similar to the filter 17 may be provided asan alternate path so that filtration can continue while the first filteris being cleaned.

Thus, it may be observed, that flow into the particulate filter 17usually will proceed serially through the filter screens 46, 47, 48, and49 and through the conduit 23 to the biological filter 22. In the eventclogging of any of these filter screens'occurs, however, overflow meansare provided for bypassing the same and, in the case of the bottomfilter 49, for returning the flow to the main tank.

A modified arrangement of the particulate filter screens of the filter17 is shown in FIG. 3. In this embodiment, the nylon mesh screens 46, 4748 and 49 are vertically disposed within the housing 45, beingsubstantially parallel to each other and to the inlet and outlet ends ofthe housing. The general water flow is in a horizontal direction fromthe inlets 16 and 21 at one end of the housing 45 to the outlet 23 atthe other, or opposite, end.

The screens 46, 47 and 48, considered from right to left, becomeincreasingly finer in mesh size, and are of substantially the samedimensions otherwise so that the tops are all positioned substantiallythe same distance below the top of the housing 45 whereby, in the caseof clogging, water can flow over the top of any screen into the nextstage for filtering through the next finer screen. The last screen 49 inthe flow path, which is the finest in mesh size, extends substantiallyto the top of the housing 45. Whenever flow through the filter screen 49becomes clogged, the overflow pipe 55 positioned between the screens 48and 49 comes into use, permitting the water flow to bypass theparticulate filter 17 and be returned to the main tank 10.

As described hereinabove, an alarm may indicate clogging or overflow, ora second particulate filter may be brought into use to provide analternate path and permit continuous filtration while the first filteris being cleaned.

Thus, in brief review, it may be seen that the present invention insuresthe maintenance of water quality in a closed cycle fish tank and watercirculation system through a novel combination of filtration elementsarranged for achieving high flow rate through the tank. Operatively,water is pumped from the fish tank to a particulate filter preferablycomprising a series of nylon mesh screens with varying size mesh insuccessive order, the screens being arranged so that any of the firstthree can be bypassed if they clog. The water descends through theparticulate filter by gravity flow to a biological filter preferablycomposed of sand and shells in which bacteria utilize the ammonia in theincoming water and convert it to nitrites and nitrates. From there,thewater descends under gravity to a sump. From the sump, water is pumpedto a manifold which feeds a bank of charcoal filters and a portion ofthis flow is tapped off and routed through an enclosure for treatmentwith ultraviolet radiation,the water from the ultraviolet treatmentsection being returned directly to the main tank. In the finalstage,filtered water is conducted from the filter bank via a pipe backto the fish tanl ,whereby high flow rate is accompanied by a consequentrate of tank water exchange and good water quality is maintained.

Additional features of the invention include the tapping off of aportion of the flow from the tank to the particulate filter and pumpingthe same through a protein skimmer for removing high molecular weightorganic material,the output of the skimmer being returned to the mainflow for passage through the particulate filter.Also,a continuouslyprimed siphon connecting the main tank and the sump for directing flowfrom either one to the other serves to maintain steady flow through thesystem.

Although the foregoing description relates primarily to pompanomariculture,in addition thereto,of course,the filtration and circulationsystem which is herein described also is useful for maintaining thewater quality in tanks for other allied species of food fish and it isintended that the extension of its use to controlling the environment ofother fish is part of the teachings thereof.

Obviously,many modifications and variations of the present invention arepossible in light of the above teachingslt is therefore to be understoodthat within the scope of the appended claims,the invention may bepracticed otherwise than as specifically described herein.

What is claimed and desired to be secured by letters patent of theUnited States is:

1. In combination with a fish tank, a filtration and circulation systemfor insuring maintenance of water quality therein,comprising:

particulate filter means,

means for pumping liquid from said fish tank to said particulate filtermeans,

biological filter means, I

conduit means connecting said biological means and said particulatefilter means,

a sump,

conduit means connecting said biological filter means and said sump,

water purifying filter means,

means for pumping water from said sump to said water purifying filtermeans, and,

conduit means connecting said water purifying filter means and saidfishtank for returning filtered water from said filter means to said tank.

2. The apparatus set forth in claim 1, wherein said particulate filtermeans comprises a series of mesh screens with decreasing size mesh inthe successive order in which water passes therethrough, and,

means for bypassing any one of said series of screens.

3.The apparatus set forth in claim 1, wherein said particulate filtermeans comprises:

a housing,

inlet means in the upper portion of said housing,

a plurality of vertically arranged,horizontally disposed mesh screensdisposed below said inlet, outlet means disposed below said meshscreens, overflow means disposed above the level of the lowermost meshscreen and below the level of the second lowermost mesh screen forreturning liquid to the fish tank when said liquid reaches the level ofsaid overflow means,and,

overflow means above the levels of all but the lowermost one of saidmesh screens for bypassing each of said screens and permitting flow tothe next lower of said screens.

4. The apparatus set forth in claim 1, further including:

means for removing high molecular weight organic material from saidliquid,

means for bypassing a portion of the liquid being pumped from said tankto said particulate filter means to said organic material removingmeans, and,

conduit means connecting said organic material removing means and saidparticulate filter means.

5. The apparatus set forth in claim 1, further comprising:

ultraviolet irradiation means,

means for bypassing a portion of the liquid being pumped from said sumpto said purifying filter means to said ultraviolet irradiation means,and,

conduit means connecting said ultraviolet irradiation means and saidfish tank.

6. The apparatus set forth in claim 1, further comprising continuouslyprimed siphon means connecting said fish tank and said sump.

7. The apparatus set forth in claim 6,further comprising particulatefilter means in said siphon means.

8. The apparatus set forth in claim 1, further comprising particulatefilter means in said means for returning said filtered water from saidpurifying filter means to said fish tank.

9. The apparatus set forth in claim 1, wherein said water purifyingfilter means is activated charcoal.

10. The apparatus set forth in claim 1, wherein said water purifyingfilter means is a resin.

11. The apparatus set forth in claim 1, wherein said water purifyingfilter means comprises a plurality of filtering units, and,

said means pumping liquid from said sump to said water purifying filtermeans includes a manifold connected with each of said plurality offiltering units.

12. The apparatus set forth in claim 1, wherein said particulate filtermeans comprises:

a housing;

inlet means in one end of said housing;

outlet means disposed in the opposite end of said housing;

a plurality of parallel, vertically disposed mesh screens horizontallyarranged in series within said housing between said inlet and outletends thereof, and

overflow means above the levels of all but the end screen nearest saidoutlet end and disposed between said end screen and the screen adjacentthereto for returning liquid to the fish tank when said liquid reachesthe level of said overflow means.

13. In combination with a fish tank, a filtration and circulation systemfor insuring maintenance of water quality therein, comprising:

particulate filter means,

means for pumping liquid from said tank to said particulate filtermeans,

means for removing high molecular weight organic material from saidliquid,

means for bypassing a portion of the flow of said liquid being pumpedfrom said tank to said particulate filter means and directing the sameto said organic material removing means,

conduit means connecting said organic material removing means and saidparticulate filter means,

biological filter means,

conduit means connecting said biological filter means and saidparticulate filter means,

a sump,

conduit means connecting said biological filter means and said sump,

water purifying filter means,

means for pumping liquid from said sump to said water purifying filtermeans, ultraviolet irradiation means, means for bypassing a portion ofthe liquid being pumped from said sump to said water purifying filtermeans and directing the same to said ultraviolet irradiation means,

conduit means connecting said ultraviolet irradiation means to said fishtank, and,

means for returning the filtered water from said water purifying filtermeans to said fish tank.

14. The apparatus set forth in claim l3,further including continuouslyprimed siphon means between said fish tank and said sump.

15. The apparatus set forth in claim 13, wherein said par ticulatefilter means comprises a series of particulate filter screens arrangedfor receiving in a successive order the liquid being received therebyfrom said fish tank and said organic material removing means,and,

means for bypassing each one of said series of screens upon cloggingthereof and directing the liquid to the next succeeding one of saidscreens in said succession of order.

16. The apparatus set forth in claim l5,wherein the bypass of the lastof said filter screens in said succession of order is connected withsaid fish tank for returning liquid thereto and thereby preventingcontamination of the remainder of said filtration system.

1. In combination with a fish tank, a filtration and circulation systemfor insuring maintenance of water quality therein, comprising:particulate filter means, means for pumping liquid from said fish tankto said particulate filter means, biological filter means, conduit meansconnecting said biological means and said particulate filter means, asump, conduit means connecting said biological filter means and saidsump, water purifying filter means, means for pumping water from saidsump to said water purifying filter means, and, conduit means connectingsaid water purifying filter means and said fish tank for returningfiltered water from said filter means to said tank.
 2. The apparatus setforth in claim 1, wherein said particulate filter means comprises aseries of mesh screens with decreasing size mesh in the successive orderin which water passes therethrough, and, means for bypassing any one ofsaid series of screens. 3.The apparatus set forth in claim 1, whereinsaid particulate filter means comprises: a housing, inlet means in theupper portion of said housing, a plurality of verticallyarranged,horizontally disposed mesh screens disposed below said inlet,outlet means disposed below said mesh screens, overflow means disposedabove the level of the lowermost mesh screen and below the level of thesecond lowermost mesh screen for returning liquid to the fish tank whensaid liquid reaches the level of said overflow means,and, overflow meansabove the levels of all but the lowermost one of said mesh screens forbypassing each of said screens and permitting flow to the next lower ofsaid screens.
 4. The apparatus set forth in claim 1, further including:means for removing high molecular weight organic material from saidliquid, means for bypassing a portion of the liquid being pumped fromsaid tank to said particulate filter means to said organic materialremoving means, and, conduit means connecting said organic materialremoving means and said particulate filter meanS.
 5. The apparatus setforth in claim 1, further comprising: ultraviolet irradiation means,means for bypassing a portion of the liquid being pumped from said sumpto said purifying filter means to said ultraviolet irradiation means,and, conduit means connecting said ultraviolet irradiation means andsaid fish tank.
 6. The apparatus set forth in claim 1, furthercomprising continuously primed siphon means connecting said fish tankand said sump.
 7. The apparatus set forth in claim 6,further comprisingparticulate filter means in said siphon means.
 8. The apparatus setforth in claim 1, further comprising particulate filter means in saidmeans for returning said filtered water from said purifying filter meansto said fish tank.
 9. The apparatus set forth in claim 1, wherein saidwater purifying filter means is activated charcoal.
 10. The apparatusset forth in claim 1, wherein said water purifying filter means is aresin.
 11. The apparatus set forth in claim 1, wherein said waterpurifying filter means comprises a plurality of filtering units, and,said means pumping liquid from said sump to said water purifying filtermeans includes a manifold connected with each of said plurality offiltering units.
 12. The apparatus set forth in claim 1, wherein saidparticulate filter means comprises: a housing; inlet means in one end ofsaid housing; outlet means disposed in the opposite end of said housing;a plurality of parallel, vertically disposed mesh screens horizontallyarranged in series within said housing between said inlet and outletends thereof, and overflow means above the levels of all but the endscreen nearest said outlet end and disposed between said end screen andthe screen adjacent thereto for returning liquid to the fish tank whensaid liquid reaches the level of said overflow means.
 13. In combinationwith a fish tank, a filtration and circulation system for insuringmaintenance of water quality therein, comprising: particulate filtermeans, means for pumping liquid from said tank to said particulatefilter means, means for removing high molecular weight organic materialfrom said liquid, means for bypassing a portion of the flow of saidliquid being pumped from said tank to said particulate filter means anddirecting the same to said organic material removing means, conduitmeans connecting said organic material removing means and saidparticulate filter means, biological filter means, conduit meansconnecting said biological filter means and said particulate filtermeans, a sump, conduit means connecting said biological filter means andsaid sump, water purifying filter means, means for pumping liquid fromsaid sump to said water purifying filter means, ultraviolet irradiationmeans, means for bypassing a portion of the liquid being pumped fromsaid sump to said water purifying filter means and directing the same tosaid ultraviolet irradiation means, conduit means connecting saidultraviolet irradiation means to said fish tank, and, means forreturning the filtered water from said water purifying filter means tosaid fish tank.
 14. The apparatus set forth in claim 13,furtherincluding continuously primed siphon means between said fish tank andsaid sump.
 15. The apparatus set forth in claim 13, wherein saidparticulate filter means comprises a series of particulate filterscreens arranged for receiving in a successive order the liquid beingreceived thereby from said fish tank and said organic material removingmeans,and, means for bypassing each one of said series of screens uponclogging thereof and directing the liquid to the next succeeding one ofsaid screens in said succession of order.
 16. The apparatus set forth inclaim 15,wherein the bypass of the last of said filter screens in saidsuccession of order is connected with said fish tank for returningliquid thereto and thereby preventing contamination of the remainder ofsaid filtration system.